1. Field of the Invention
This invention relates to new photoacid generator compounds (xe2x80x9cPAGsxe2x80x9d) and photoresist compositions that comprise such compounds. In particular, the invention relates to substituted disulfone compounds, including disulfone compounds that contain a diazo, substituted methylene or hydrazine moiety interposed between two substituted sulfone groups.
2. Background
Photoresists are photosensitive films for transfer of images to a substrate. They form negative or positive images. After coating a photoresist on a substrate, the coating is exposed through a patterned photomask to a source of activating energy such as ultraviolet light to form a latent image in the photoresist coating. The photomask has areas opaque and transparent to activating radiation that define an image desired to be transferred to the underlying substrate. A relief image is provided by development of the latent image pattern in the resist coating. The use of photoresists is generally described, for example, by Deforest, Photoresist Materials and Processes, McGraw Hill Book Company, New York (1975), and by Moreau, Semiconductor Lithography, Principals, Practices and Materials, Plenum Press, New York (1988).
Known photoresists can provide features having resolution and size sufficient for many existing commercial applications. However for many other applications, the need exists for new photoresists that can provide highly resolved images of submicron dimension.
Various attempts have been made to alter the make-up of photoresist compositions to improve performance of functional properties. Among other things, a variety of photoactive compounds have been reported for use in photoresist compositions. See, e.g., U.S. Pat. No. 4,450,360 and European Application 615163.
More recently, certain xe2x80x9cchemically amplifiedxe2x80x9d photoresist compositions have been reported. Such photoresists may be negative-acting or positive-acting and rely on multiple crosslinking events (in the case of a negative-acting resist) or deprotection reactions (in the case of a positive-acting resist) per unit of photogenerated acid. In other words, the photogenerated acid acts catalytically. In the case of positive chemically amplified resists, certain cationic photoinitiators have been used to induce cleavage of certain xe2x80x9cblockingxe2x80x9d groups pendant from a photoresist binder, or cleavage of certain groups that comprise a photoresist binder backbone. See, for example, U.S. Pat. Nos. 5,075,199; 4,968,851; 4,883,740; 4,810,613; and 4,491,628, and Canadian Patent Application 2,001,384. Upon selective cleavage of the blocking group through exposure of a coating layer of such a resist, a polar functional group is provided, e.g., carboxyl, phenol or imide, which results in different solubility characteristics in exposed and unexposed areas of the resist coating layer.
We have now discovered novel photoacid generator compounds (PAGs) for use in either positive-acting or negative-acting photoresist compositions. PAGs of the invention contain a disulfone groups, including disulfone compounds that contain a diazo, substituted methylene or hydrazine moiety interposed between two substituted sulfone groups.
More particularly, in a first aspect of the invention, substituted diazodisulfone PAGs are provided that comprise one or more substituents of: phenyl having one or more electron-withdrawing ring substituents; an optionally substituted alicyclic group, particularly polycyclic groups having 2, 3, 4 or more fused, bridged or otherwise linked rings such as adamantyl, pinanyl, fencyl, tricyclodecane, and the like; optionally substituted naphthyl; optionally substituted thienyl; optionally substituted coumarinyl; optionally substituted quinolinyl; optionally substituted furyl; optionally substituted thiazolyl; optionally substituted oxazolyl; optionally substituted benzofuranyl; optionally substituted benzothiazolyl; or optionally substituted tetrahydrofuranyl.
Particularly preferred substituted diazodisulfone PAGs of the invention include those of the following Formula I: 
wherein R and R1 at least one of R and R1 is phenyl having one more phenyl-ring electron-withdrawing substituents; an optionally substituted alicyclic group; optionally substituted naphthyl; optionally substituted thienyl; optionally substituted coumarinyl; optionally substituted quinolinyl; optionally substituted furyl; optionally substituted thiazolyl; optionally substituted oxazolyl; optionally substituted benzofuranyl; optionally substituted benzothiazolyl; or optionally substituted tetrahydrofuranyl. Formula I is further discussed below.
In a further aspect of the invention, substituted xcex1,xcex1-methylenedisulfone PAGs are provided, wherein preferably the methylene (e.g. C(R2)(R3) as R2 and R3 are shown in Formula II below) interposed between the two sulfone moieties is mono- or di-substituted with non-hydrogen substituents.
Preferred substituted xcex1,xcex1-methylenedisulfone PAGs of the invention include those of the following Formula II: 
wherein R and R1 are the same or different and are other than hydrogen;
R2 and R3 are the same or different and may be hydrogen or a non-hydrogen substituent;
and preferably at least one of R2 and R3 is other than hydrogen, more preferably both R2 and R3 are other than hydrogen. Formula II is further discussed below.
In a still further aspect of the invention, substituted disulfonehydrazine (hydrazine moiety interposed between the two sulfone moieties) PAGs are provided, wherein preferably the hydrazine moiety (e.g. xe2x80x94N(R2)xe2x80x94N(3)xe2x80x94 of Formula III below) interposed between the two sulfone moieties is mono- or di-substituted with non-hydrogen substituents.
Preferred substituted disulfonehydrazine PAGs of the invention include those of the following Formula III: 
wherein R and R1 are the same or different and are other than hydrogen;
R2 and R3 are the same or different and may be hydrogen or a non-hydrogen substituent;
and preferably at least one of R2 and R3 is hydrogen, more preferably both R2 and R3 are hydrogen. Formula III is further discussed below.
Preferred compounds of the invention also disulfone compounds, where no carbons or other atoms are interposed between the sulfone groups. Preferred disulfone compounds include both unsymmetrical and symmetrical PAGs of the following Formulae IVA and IVB: 
wherein in Formula IVA, X and Y are different and are selected from the group consisting of optionally substituted naphthyl including optionally substituted 1-naphthyl and optionally substituted 2-naphthyl; pentafluorophenyl; optionally substituted thienyl (including optionally substituted 2-thienyl); perfluoroalkyl particularly perfluoroC1-12alkyl or perfluoroC1-8alkyl such as CF3 and the like; 2,2,2-trifluoroethyl; optionally substituted o-(trifluoromethyl)phenyl; optionally substituted adamantyl (particularly 1-adamantyl); optionally substituted camphoryl (particularly 10-camphoryl); optionally substituted cyclohexyl; and optionally substituted t-butyl, with the exclusion where X is camphoryl and Y is naphthyl; and
wherein in Formula IVB, Xxe2x80x2 and Yxe2x80x2 are the same and are selected from perfluoroalkyl particularly perfluoroC1-12alkyl or perfluoroC1-8alkyl such as CF3 and the like; optionally substituted camphoryl (particularly 10-camphoryl); optionally substituted o-(trifluoromethyl)phenyl; optionally substituted thienyl including optionally substituted 2-thienyl; optionally substituted adamantyl) (particularly (1-adamantyl); and optionally substituted t-butyl.
Preferably, PAGs of the invention are used in positive-acting or negative-acting chemically amplified photoresists, i.e. negative-acting resist compositions which undergo a photoacid-promoted crosslinking reaction to render exposed regions of a coating layer of the resist less developer soluble than unexposed regions, and positive-acting resist compositions which undergo a photoacid-promoted deprotection reaction of acid labile groups of one or more composition components to render exposed regions of a coating layer of the resist more soluble in an aqueous developer than unexposed regions. Preferred imaging wavelengths include sub-300 nm wavelengths e.g. 248 nm, and sub-200 nm wavelengths e.g. 193 nm and sub-170 nm such as 157 nm.
The invention also provide methods for forming relief images of the photoresists of the invention, including methods for forming highly resolved patterned photoresist images (e.g. a patterned line having essentially vertical sidewalls) of sub-micron and even sub-half or sub-quarter micron dimensions.
The invention further provides articles of manufacture comprising substrates such as a microelectronic wafer or a flat panel display substrate having coated thereon the photoresists and relief images of the invention. Other aspects of the invention are disclosed infra.